Generally, a lightning arrester is installed at the uppermost part of a building to form a discharge path between a thundercloud and the ground to safely flow charges accumulated in the thundercloud to the ground.
When a normal thundercloud approaches the ground, an electric potential difference between the thundercloud and the ground is about one hundred million volts.
In this state, the air in the atmospheric layer functions as a good insulating body to prevent insulation breakdown between the ground and the thundercloud, i.e., a lightning. However, the probability of generating a lightning between the thundercloud and the ground is still in existence.
A lightning arrester using an electric field phenomenon (tip effect) in which an electric field is concentrated to a tip part is referred to as a Franklin rod type.
A theory of a lightning rod using the tip effect is disclosed in Japanese Patent Laid-open Publication No. S62-216197 (Sep. 22, 1987).
The lightning rod using the tip effect uses a natural phenomenon only. Since the lightning rod is operated only when breakdown of an insulation voltage of the air occurs, it is difficult to effectively prevent a lightning in the case that the thundercloud has a hazard just before breakdown of an insulation voltage. For this reason, in this field, various types of lightning arresters have been developed to more effectively and safely discharge charges in the thundercloud to the ground to reduce the number of lightning to an object to be protected.
For example, Korean Utility Model Application No. 2000-13418 discloses an ion radiation lightning rod capable of automatically radiating charges on the ground formed by a thundercloud to collect energy of a downward leader generated during lightning, i.e., drawing the lightning occurring therearound to the lightning rod.
However, the ion radiation lightning rod may also cause huge damage similar to the conventional lightning rod. In addition, a lightning counter should be installed to cause the lightning rod to be complicated, thereby increasing manufacturing cost. Further, since an installation height of the lightning rod is too high, it is difficult to install the lightning rod at the building, and appearance of the building may be deteriorated.
Meanwhile, in order to solve the problem, a lightning arrester is disclosed in Korean Utility Model Registration No. 330621.
As shown in FIG. 1, a lightning arrester 200 of Utility Model Registration No. 330621 includes a lightning rod 100 having splines 1 disposed in a radial manner and formed of a plurality of stainless steel wires, a core 3 formed of four to eight stainless steel wires twisted with each other and supporting the splines 1 at its upper end, a fixing adaptor 2 for collecting one ends of the splines 1 to fix them to an upper end of the core 3, filaments 4 radially twisted with the core 3 and disposed in an outer radial direction of the core 3, and a support adaptor 5 having a threaded part 6 at its lower end; and a lightning rod mounting base 110 formed of a circular metal plate and having bolt holes 13 for fixing the lightning rod mounting base using bolts.
The splines 1 are formed of stainless steel wires having a diameter of about 1 mm and a length of about 25 cm. Here, in order to effectively move charges, ends of the splines 1 are cut at 45. About sixty splines 1 may be provided. The fixing adaptor 2 fixes the splines 1, and is fixed to the upper end of the core 3 through welding, or the like. That is, the plurality of splines 1 are formed of stainless steel wires having one ends inserted into the fixing adaptor 2, and the fixing adaptor 2 is fixed to the core 3 at its lower end through tag welding, or the like.
The splines 1 are aligned in parallel before the lightning arrester 200 is installed at a building or a structure, and radially arranged in a semi-spherical shape as shown in FIG. 1 after the lightning arrester 200 is installed.
The core 3 is formed of four stainless steel wires having a diameter of 3 mm, which are twisted with each other, thereby securely fixing the splines 1 thereon. The filaments 4 are formed of about fifteen hundreds of stainless steel wires having a diameter of 0.1 mm, which are twisted with the core 3 in a radial direction. Here, the filaments 4 are cut at 45 at their ends. The filaments 4 may have a length of about 10 cm.
The support adaptor 5 fixes the core 3 and the filaments 4 radially fixed to the core 3 using welding, or the like. The threaded part 6 is formed at the lower end of the support adaptor 5 and inserted into a female threaded part 15 of the lightning rod mounting base 110, thereby securely fixing the lightning rod 100 to the lightning rod mounting base 110.
The lightning rod mounting base 110 is formed of a circular iron plate, and has the female threaded part 15 for fixing the lightning rod 100 and bolt holes 13 for securely fixing the lightning rod mounting base 110 to a bottom surface. A ground cable 14 and a ground cable fixture 11 are fixed to the lightning rod mounting base 110 using bolts 12.